Field of the Invention
The present invention relates to an image display device, and more particularly, to a full-flat image display device provided with a touch switch.
Description of the Related Art
In recent years, as image display devices, there are known full-flat image display devices whose display screen and frame are integrated. Compared to a conventional image display device whose display screen and frame are separated, a full-flat image display device is superior in design due to its sense of unity and the part of the frame is not conspicuous thanks to the sense of unity, and when the image display devices are arranged next to each other, viewers get an impression that the image display devices are smoothly connected. Therefore, a market demand for full-flat image display devices is on the increase.
To realize a touch panel of a full-flat image display device, a capacitive touch panel is desirable, which is operated based on a change in capacitance that is caused when a fingertip or the like comes close to known glass, by using a method of detecting a touch on the glass (for example, see JP 2013-106308 A).
Furthermore, in recent years, there is a trend to increase a size of a screen of an image display device, and a large screen is also demanded for a full-flat image display device. In the case of a large-screen image display device, in order to secure a strength, glass on the whole surface of a display screen is possibly made very thick, and for example, in the case of art 80-inch display, a thickness of 3 mm or more is required.
Accordingly, to provide a mechanical operation button to a frame part of a large-screen foil-flat image display device, a hole needs to be made to thick, large glass, and there are problems that processing is not easy and the cost is high.
It is conceivable to provide a capacitive touch switch to the frame, instead of a mechanical operation button, but in this case, an area of a capacitance detection, sheet for detecting a change in capacitance has to be spread to the frame part.
However, normally, a capacitance detection sheet is made according to a size of a display screen, and cannot be used for a power switch or the like positioned at the frame part outside the display screen. Also, in the case of using a capacitance detection sheet which is larger than the display screen, the frame part spreads also to parts other than a part where a power switch or the like is disposed, and thus the design is impaired, and a problem is caused at a time when a multi-screen is structured by combining a plurality of image display devices next to one another. Also, there is a problem that ordering a capacitance detection sheet which is not in accordance with a size of a display screen increases burden of cost.
It is also conceivable to configure a touch panel and switch by connecting a plurality of small-area capacitance detection sheets, but in this case, components other than the small-area capacitance detection sheets, such as cable wires for connecting the capacitance detection sheets, become necessary, and there are problems that burden of cost is increased, and also, that assembly efficiency is deteriorated.